Lava fields and in dry forest, mesic forest, and subalpine shrubland
Elevation
520-2380 m
Habit
Perennials with short, decumbent rhizomes clothed with brown or yellowish brown old sheaths and their fibrous remnants; culms densely tufted, (12-)20-70 cm tall, 2-4 mm in diameter in lower part, obtusely trigonous, smooth, 1-3 nodose between the base and inflorescence.
Leaves
Leaves numerous, primarily basal, only 1-3 cauline, blades linear, longer than the culm, 2-8 mm wide, margins scabrous, strongly revolute, gradually tapering to a long acuminate apex; sheaths brown or yellowish brown, disintegrating into parallel fibers.
Flowers
Inflorescence an erect, compound panicle (5-)10-35 cm long, 1-2.5 cm wide, bearing 3-7 small partial panicles, moderately dense in upper part, lax and slightly interrupted toward base, leafy bracts usually longer than the inflorescence, the sheathing base tinged brown, 1-4 cm long, peduncles solitary in lower part of inflorescence, the upper ones in groups of 2-4, mostly enclosed in the bract sheath; spikelets clustered in groups of 2 to several, each one narrowly ovoid, 8-10 mm long, 2-3 mm wide, acuminate; glumes brown, 6-8, 2 ranked, disarticulating at base, deciduous, the lower 4-6 glumes chartaceous, empty, narrowly ovate, gradually narrowed to acuminate or short awned apex, hispidulous in upper part, the remaining 2 glumes subtending the achene 7-8 mm long, much longer than the lower ones, apex subacute; stamens 3; filaments persistent at base of achene and the distal part held within the convolute apex of the subtending glume, hence the mature achenes pendent on the inflorescence for awhile; style ca. 5 mm long, the base remaining at achene apex as a subulate mucro.
Fruit
Achenes ovoid ellipsoid to ellipsoid, 2.7-3 mm long, ca. 2 mm wide, maturing black, slightly glossy, rounded at both ends.
